Background: Abnormally low or high blood iron levels are common health conditions worldwide and can seriously affect an individual's overall well-being. A low-cost point-of-care technology that measures blood iron markers with a goal of both preventing and treating iron-related disorders represents a significant advancement in medical care delivery systems. Methods A novel assay equipped with an accurate, storable, and robust dry sensor strip, as well as a smartphone mount and (iPhone) app is used to measure total iron in human serum. The sensor strip has a vertical flow design and is based on an optimized chemical reaction. The reaction strips iron ions from blood-transport proteins, reduces Fe(III) to Fe(II), and chelates Fe(II) with ferene, with the change indicated by a blue color on the strip. The smartphone mount is robust and controls the light source of the color reading App, which is calibrated to obtain output iron concentration results. The real serum samples are then used to assess iron concentrations from the new assay, and validated through intra-laboratory and inter-laboratory experiments. The intra-laboratory validation uses an optimized iron detection assay with multi-well plate spectrophotometry. The inter-laboratory validation method is performed in a commercial testing facility (LabCorp). Results: The novel assay with the dry sensor strip and smartphone mount, and App is seen to be sensitive to iron detection with a dynamic range of 50-300 μg/dL, sensitivity of 0.00049 a.u/μg/dL, coefficient of variation (CV) of 10.5%, and an estimated detection limit of ~15 μg/dL These analytical specifications are useful for predicting iron deficiency and overloads. The optimized reference method has a sensitivity of 0.00093 a.u/μg/dL and CV of 2.2%. The correlation of serum iron concentrations (N=20) between the optimized reference method and the novel assay renders a slope of 0.95, and a regression coefficient of 0.98, suggesting that the new assay is accurate. Last, a spectrophotometric study of the iron detection reaction kinetics is seen to reveal the reaction order for iron and chelating agent. Conclusion: The new assay is able to provide accurate results in intra-and inter-laboraty validations, and has promising features of both mobility and low-cost manufacturing suitable for global healthcare settings.

Complex graphene electrode fabrication protocols including conventional chemical vapor deposition and graphene transfer techniques as well as more recent solution‐phase printing and postprint annealing methods have hindered the wide‐scale implementation of electrochemical devices including solid‐state ion‐selective electrodes (ISEs). Herein, a facile graphene ISE fabrication technique that utilizes laser induced graphene (LIG), formed by converting polyimide into graphene by a CO2 laser and functionalization with ammonium ion (NH4+) and potassium ion (K+) ion‐selective membranes, is demonstrated. The electrochemical LIG ISEs exhibit a wide sensing range (0.1 × 10−3–150 × 10−3 m for NH4+ and 0.3 × 10−3–150 × 10−3 m for K+) with high stability (minimal drop in signal after 3 months of storage) across a wide pH range (3.5–9.0). The LIG ISEs are also able to monitor the concentrations of NH4+ and K+ in urine samples (29–51% and 17–61% increase for the younger and older patient; respectively, after dehydration induction), which correlate well with conventional hydration status measurements. Hence, these results demonstrate a facile method to perform in‐field ion sensing and are the first steps in creating a protocol for quantifying hydration levels through urine testing in human subjects.

Weight disorders are strikingly prevalent globally and can contribute to a wide array of potentially fatal diseases spanning from type II diabetes to coronary heart disease. These disorders have a common cause: poor calorie balance. Since energy expenditure (EE) (kcal d−1) constitutes one half of the calorie balance equation (the other half being food intake), its measurement could be of great value to those suffering from weight disorders. A technique for contact free assessment of EE is presented, which only relies on CO2 concentration monitoring within a sealed office space, and assessment of carbon dioxide production rate (VCO2). Twenty healthy subjects were tested in a cross-sectional study to evaluate the performance of the aforementioned technique in measuring both resting EE (REE) and exercise EE using the proposed system (the ‘SmartPad’) and a U.S. Food and Drug Administration (FDA) cleared gold standard reference instrument for EE measurement. For VCO2 and EE measurements, the method showed a correlation slope of 1.00 and 1.03 with regression coefficients of 0.99 and 0.99, respectively, and Bland–Altman plots with a mean bias = −0.232% with respect to the reference instrument. Furthermore, two subjects were also tested as part of a proof-of-concept longitudinal study where EE patterns were simultaneously tracked with body weight, sleep, stress, and step counts using a smartwatch over the course of a month, to determine correlation between the aforementioned parameters and EE. Analysis revealed moderately high correlation coefficients (Pearson’s r) for stress (r average = 0.609) and body weight (r average = 0.597) for the two subjects. The new SmartPad method was demonstrated to be a promising technique for EE measurement under free-living conditions.

Disorders in iron metabolism are endemic globally, affecting more than several hundred million individuals and often resulting in increased mortality rates or general deterioration of quality of life. To prevent and monitor iron-related disorders, we present a point of care multiplex system to measure four clinically relevant iron biomarkers: blood iron levels (iron bound to transferrin), total iron-binding capacity (TIBC), percent transferrin saturation, and blood ferritin. This system leverages three distinct channels: two colorimetric and one electrochemical emerging from the same sample injection port designed to accommodate 50 ul of whole blood, filter out cellular components, and transport the filtered sample to the three specified channels’ capillary action. The first channel measures iron levels. It uses a membrane impregnated with the working reagents that reduce iron (III) to iron (II) and chelate the reduced iron with ferene forming a blue- complex. A custom smartphone app quantifies the Fe-ferene complex and provides outputs iron levels in whole blood. The second channel measures TIBC. This channel uses the same membrane and detection method that the first channel but requires an extra preconditioning step of saturating the blood sample with iron standard and precipitating excess unbound iron with a specific binding agent (magnesium carbonate). Using the ratio of total iron (output of channel 1) and TIBC (output of channel 2) enables calculating the percentage of transferrin saturation. The two colorimetric channels were created at Forzani’s Team at Arizona State University, while the electrochemical channel is created by Diez-Perez’s Team at King’s College London. The detection of Ferritin consists of a novel method that combines the selectivity of antibodies with the electrochemical properties of Ferritin for high sensitivity detection. The sensor components are all 3D-printed and require a finger-prick sample for complete measurement of these clinically relevant iron biomarkers. Iron biomarkers. Comparative studies of results obtained by the new sensing device and the reference method in actual samples were performed to determine the device’s capacity to detect iron parameters’ concentrations. Correlation plots with a slope of ~ 1 and regression coefficient of higher than 0.82 were obtained for detection of blood iron levels, total iron-binding capacity, and percentage of transferrin saturation. This indicated that the new device is substantially equivalent to the reference method. With detection times of five minutes, fingerpick sample, and sensor cost less than 10 cents; the device shows excellent promise for point care testing of iron disorders.

Disorders in iron metabolism are endemic globally, affecting more than several hundred million individuals and often resulting in increased rates of mortality or general deterioration of quality of life. To...